The present invention relates to an irrigation system and more particularly a system for supplying water onto an extensive area of land.
When water is supplied onto land for irrigation purposes sprinklers are attached to a water supply line disposed on the ground to eject water therethrough. If the area of the land to be irrigated is small, this water supply system is satisfactory. However, in cases where the land to be irrigated is large, this sprinkler system is not suitable because of the limit of the water supply capacity.
Therefore, mobile type irrigation machines have been used for irrigation of large areas of land. When mobile type irrigation machines are used, a water supply line has to be located on the land to be irrigated and valve assemblies are provided thereon equally spaced from each other. The irrigation machine is advanced along the water supply line, and while advancing, the machine is connected to the valve assemblies step-by-step so that the machine receives water from the water supply line and sprinkles water therefrom.
U.S. Pat. Nos. 4,036,436 and 4,172,556 relate to a self-propelled linear irrigation system in which a tractor is moved along a water supply line to supply water onto the ground from the water supply line. The tractor comprises a central rigid section and front and rear valve cars connected to the central section. The central section moves constantly, but the front and rear valve cars move intermittently so that one of the cars is always connected to the water supply line. Consequently, water is supplied from one of the cars to the central section and the water sprinkles therefrom.
U.S. Pat. No. 4,274,584 also relates to a land irrigation system in which an irrigation machine comprises a tractor, and two pipe assemblies movably connected to the front and rear ends of the tractor. The machine moves constantly along a water supply line, but the pipe assemblies move intermittently so that one of the pipe assemblies is always connected to the water supply line to sprinkle water from the tractor.
The above prior art devices involve large equipment and three moving parts always have to be controlled properly. Therefore, such prior irrigation machines are complicated and are not easily operated.
Accordingly, an object of the invention is to provide an irrigation system in which, when an irrigation machine is moved constantly along a water supply line, the irrigation machine automatically receives water from the water supply line and sprinkles water onto the land.
Another object of the invention is to provide an irrigation system which can be operated at low cost and low maintenance with high reliability.
A further object of the invention is to provide an irrigation machine for sprinkling water onto land, which can operate simply by moving the irrigation machine along the water supply line.
A still further object of the invention is to provide an irrigation machine in which all the moving parts can be controlled and operated by water supplied from a water supply line without an external source of energy.
A still further object of the invention is to provide an irrigation machine in which the energy sequence of operation is positive and depends directly on the previous operation.
A still other object of the invention is to provide a method of irigating land along a water supply line which can be simply and reliably operated.
A still further object of the invention is to provide a valve assembly adapted to use for a water supply line for irrigation.
Further objects and advantages of the invention will be apparent from the following description of the invention.